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Herein, using Fe 3 O 4 nanoparticles (Fe 3 O 4 NPs) as a magnetic artificial peroxidase, an "on-off" ratiometric photoluminescence sensor with high-sensitivity and high-selectivity for coumarin was constructed based on photoinduced electron transfer (PET) between 7-hydroxycoumarin and rhodamine B (RB). The results showed that Fe 3 O 4 NPs catalyzed H 2 O 2 to generate nucleophilic group ·OH, which attacked the active site of coumarin and produced strong fluorescent 7-hydroxycoumarin molecules. Then, the fluorescence of RB was quenched with 7-hydroxycoumarin through the PET effect. The ratio signal generated in the above process was used for the quantitative detection of coumarin. Under optimized conditions, the linear range 0.5-25 mg/L was acquired for coumarin with the detection limit of 0.016 mg/L. This method had excellent selectivity and the recovery rate was 81.8%-106.8% with the relative standard deviation less than 5.6%, so it can be used for the quantitative analysis of coumarin in complex matrix samples., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Recently, studies showed that the drug-resistant cell membranes have formed high-density lipid rafts regions; traditional targeted drug delivery systems can hardly break through the hard shell and deliver drugs to drug-resistant cells. Here, α-tocopherol polyethylene glycol 2000 succinate (TPGS 2k ) was successfully synthesized and used to modify poly (lactic-glycolic acid) nanoparticles co-loaded with doxorubicin (DOX) and simvastatin (SV) (SV/DOX@TPGS 2k -PLGA NPs). The purpose of this study is to explore the synergistic effect between SV consuming cholesterol in lipid rafts and directly down-regulating P-gp expression on the intracellular drugs retention. The research highlights these nanoparticles interrupted lipid rafts (cholesterol-rich domains, where P-gp is often located), which inhibited drug efflux by down-regulating P-gp, promoted the mitochondria apoptosis and made SW620/AD300 cells (DOX-resistant colon cancer cell line) re-sensitized to DOX. Therefore, the carrier can become a promising SV-based nano-delivery system with depleting cholesterol in lipid rafts to reverse drug resistance., (Copyright © 2020. Published by Elsevier Inc.)

Currently, immunochemotherapy based on tumor-associated macrophages (TAMs) is mainly used for elimination of M2 macrophages. However, these methods cannot make full use of the positive immune-modulatory effects of macrophages. This study explores a two-way cruise strategy for combining immunotherapy based on TAM phenotype reversal with classical chemotherapy, the nanosatellites (DOX@HFn-PGZL@Res) are proposed to accurately deliver the chemotherapeutic agents and immune activators to their respective target cells. When the delivery system is recruited to tumor microenvironment, the nanosatellites are separated into DOX@HFn and Res@GZL nanoparticles, which can enter cancer cells and M2-TAMs, respectively. The data show that DOX@HFn-PGZL@Res successfully re-educate M2 to M1 macrophages, resulting in an activated immune response and inhibition of tumor invasion and metastasis. In general, this work describes a two-way homing nanoplatform for the integration of immunotherapy and chemotherapy, which provides a new idea for the "attack-defense" integrated treatment of tumor.

Transcription factors (TFs) regulate gene expression by binding to regulatory regions, and their dysregulation is involved in numerous diseases. Thus, they are therapeutic targets and potential diagnostic markers. However, widely used methods for TFs detection are either cumbersome or costly. Herein, we first applied DNA-Ag nanoclusters molecular beacons (AgMBs) in TFs analysis and designed an assay based on the switchable fluorescence of AgMBs. In the absence of TFs, a single-stranded DNA functioned as a reporter is released from a double-stranded DNA probe (referred as dsTFs probe) under exonuclease III (Exo III) digestion. Then, the reporter triggers downstream Exo III-assisted signal amplification by continuously consuming the guanine-rich enhancer sequences in AgMBs, resulting in significant fluorescent decrease eventually. Conversely, the presence of TFs protects the dsTFs probe from digestion and blocks the downstream reaction to keep a highly fluorescent state. To testify this rationale, we utilized nuclear factor-kappa B p50 (NF-κB p50) as a model TFs. Owing to the amplification strategy, this method exhibited high sensitivity toward NF-κB p50 with a limit of detection of 10 pM, and a broad linear range from 30 pM to 1.5 nM. Furthermore, this method could detect multiple TFs in human colon cancer DLD-1 cells and reflect the variation in their cellular levels after stimulation. Finally, by conducting an inhibition assay we revealed the potential of this method for screening TFs-targeted drugs and calculating the IC 50 of corresponding inhibitors.

A molecularly imprinted stir bar was constructed based on Fe3O4@Polyaniline nanoparticles with magnetic field-induced self-assembly process. The monomer, methacrylic acid, was pre-assembled into the pre-polymers with vanillin as template by the formation of hydrogen bonds. After that, the magnetic complexes were generated by the hydrogen bonding, the hydrophobic and π-π interaction between the pre-polymers and Fe3O4@Polyaniline. The complexes were adsorbed on the surface of magnetic stir bar under the magnetic induction, and the coating of vanillin-molecularly imprinted polymers was generated by the one-step copolymerization basing on the cross linking of ethylene glycol dimethacrylate. The molecular imprinting stir bar showed superior selectivity and fast binding kinetics for vanillin, and was used for the enrichment of vanilla-flavor enhancers (vanillin, ethyl maltol and methyl vanillin) in infant milk powders. The results measured by HPLC-UV exhibited good linear ranges of 0.01-100, 0.02-100 and 0.03-100μgmL(-1) with the limit of detection of 2.5-10.0ngmL(-1), and the recoveries were 94.7-98.9%, 82.1-96.7% and 84.5-93.2% with RSD<7.2% for the three enhancers, respectively., (Copyright © 2014 Elsevier Inc. All rights reserved.)

A novel electrochemical sensing platform based on magnetic field-induced self-assembly of Fe3O4@Polyaniline nanoparticles (Fe3O4@PANI NPs) has been for the first time fabricated for the sensitive detection of creatinine in biological fluids. The template molecule, creatinine, was self-assembled on the surface of Fe3O4@PANI NPs together with the functional monomer aniline by the formation of N-H hydrogen bonds. After pre-assembled, through the magnetic-induction of the magnetic glassy carbon electrode (MGCE), the ordered structure of molecularly imprinted polymers (MIPs) were established by the electropolymerization and assembled on the surface of MGCE with the help of magnetic fields by a simple one-step approach. The structural controllability of the MIPs film established by magnetic field-induced self-assembly was further studied. The stable and hydrophilic Fe3O4@PANI can not only provide available functionalized sites with which the template molecule creatinine can form hydrogen bond by the abundant amino groups in PANI matrix, but also afford a promoting pathway for electron transfer. The as-prepared molecularly imprinted electrochemical sensor (MIES) shows good stability and reproducibility for the determination of creatinine with the detection limit reached 0.35 nmol L(-1) (S/N=3). In addition, the highly sensitive and selective MIES has been successfully used for the clinical determination of creatinine in human plasma and urine samples. The average recoveries were 90.8-104.9% with RSD lower than 2.7%., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Abstract: A novel electrochemical sensing platform based on magnetic field-induced self-assembly of Fe3O4@Polyaniline nanoparticles (Fe3O4@PANI NPs) has been for the first time fabricated for the sensitive detection of creatinine in biological fluids. The template molecule, creatinine, was self-assembled on the surface of Fe3O4@PANI NPs together with the functional monomer aniline by the formation of N–H hydrogen bonds. After pre-assembled, through the magnetic-induction of the magnetic glassy carbon electrode (MGCE), the ordered structure of molecularly imprinted polymers (MIPs) were established by the electropolymerization and assembled on the surface of MGCE with the help of magnetic fields by a simple one-step approach. The structural controllability of the MIPs film established by magnetic field-induced self-assembly was further studied. The stable and hydrophilic Fe3O4@PANI can not only provide available functionalized sites with which the template molecule creatinine can form hydrogen bond by the abundant amino groups in PANI matrix, but also afford a promoting pathway for electron transfer. The as-prepared molecularly imprinted electrochemical sensor (MIES) shows good stability and reproducibility for the determination of creatinine with the detection limit reached 0.35nmolL−1 (S/N=3). In addition, the highly sensitive and selective MIES has been successfully used for the clinical determination of creatinine in human plasma and urine samples. The average recoveries were 90.8–104.9% with RSD lower than 2.7%. [Copyright &y& Elsevier]

A novel label-free and exonuclease III (Exo III)–assisted signal amplification electrochemical aptasensor was constructed for the determination of carcinoembryonic antigen (CEA) via magnetic field–induced self-assembly of magnetic biocomposites (Fe3O4@Au NPs-S1-S2-S3). The magnetic biocomposites were acquired by modifying double-stranded DNA (S1-S2-S3) on the surface of Fe3O4@Au nanoparticles (Fe3O4@Au NPs). Among them, Fe3O4@Au NPs were used as carriers for magnetic separation, thiolated single-stranded DNA (S1) provided signal sequence, CEA aptamer (S2) worked as a recognition element, and complementary strand (S3) was used to form double strands. In the presence of CEA, S2 bonded with CEA competitively; the exposed S1 could not be cleaved since Exo III was inactive against ssDNA. The G-quadruplex/hemin complexes finally formed with the existence of K+, and the high electrochemical signal of G-quadruplex/hemin complexes was recorded by differential pulse voltammetry (DPV) at − 0.6 V. Conversely, in the absence of CEA, dsDNA was cleaved from the 3′ blunt end by Exo III; the disappearance of G-rich sequence blocked the generation of the signal. This method exhibited good selectivity and sensitivity for the determination of CEA; the linear range was from 0.1 to 200 ng mL−1 and the limit of detection was 0.4 pg mL−1. [ABSTRACT FROM AUTHOR]

The molecularly imprinted magnetic stir bar coatings were created based on graft-functional Fe 3 O 4 nanoparticles with magnetic field-induced self-assembly. The magnetic complex including clonazepam as template, the graft-functional Fe 3 O 4 nanoparticles and methacrylic acid as monomers was pre-assembled through π–π interaction and hydrogen bonding, then was directionally adsorbed on the surface of magnetic stir bar under the magnetic induction. The molecularly imprinted coating with well-ordered structure was generated by one-step copolymerization based on the cross linking of ethylene glycol dimethacrylate. The molecularly imprinted coating with multiple recognition sites could be manufactured and applied in polar solvents, and showed superior selectivity and fast binding kinetics for benzodiazepines. The analytes in herbal health foods, treated by stir bar sorptive extraction, were determined by HPLC-UV. Good linearity was observed in the range of 0.01–2 μg mL −1 . The content of clonazepam in the herbal health foods was found to be 44 ng g −1 , and the average recoveries were 89.8–103.3% with a relative standard deviation (RSD) <6.5%, demonstrating the successful application in real sample analysis. [ABSTRACT FROM AUTHOR]